A force moment sensor allows for the sensing of six degrees of freedom force measurement. Dexterous tasks in close proximate operations where camera views are insufficient need these senses of touch to avoid overloading both the payloads they are handling and themselves. A force moment sensor is an instrument that typically is integrated into a robotic arm. It is particularly useful in space applications as well as underwater applications.
Space robotic operations take place over extended time frames (hours to days), under fluctuating temperature environments, on a flexible robotic arm. The need to capture ‘free flying’ bodies (ie spacecraft which are ‘freely floating’ with respect to the capturing robot) is a further challenge over those of terrestrial environments.
Lack of atmosphere drives temperatures to be either hot in sun or cold in shade. Since robots are typically used for moving things around, so they go into and out of shade repeatedly.
There are a number of challenges when determining the force and moment applied to a robotic arm in an unknown environment. These challenges are even more difficult in a space environment. Typically force is not directly measurable. It can be inferred from strain or deflection. However, such measures are affected by thermal distortion. It is well known that long robot arms and the need to capture ‘free flyers’ generate large rotational forces. In addition, a high stiffness requirement makes measurement of strain or deflection more difficult to isolate from thermal distortion. Further, drift in space operations tend to be slow—often taken over a period of hours. Still further, it is important to distinguish all 6 degrees of force measurement, but the shear and moment loading cases can produce difficult to distinguish effects
Accordingly a force moment sensor designed for use in space or underwater would be desirable.